Symmetric encryption generally is ok/only weakened, and there's lots of research into solutions: https://en.wikipedia.org/wiki/Post-quantum_cryptography

To our knowledge, it cannot. It would be extremely surprising if it could.

However, it can reduce the difficulty of a generic brute force search

https://en.wikipedia.org/wiki/Grover%27s_algorithm

But it only reduces the effective key length by 2. Which, although amazing, has a fairly straightforward response. Double your key length beyond what was previously viewed as 'intractable'.

They break all widely used public key encryption systems (RSA, DH, ECC-based). There are post-quantum systems, but none of them are in widespread use yet.

Symmetric encryption systems are weakened, but can easily be made quantum safe by increasing the key size.

Nothing can break a one time pad, used for the super secure stuff.

Yes, good point.